1951 — June 30, United Flight 610 flies into Crystal Mountain, 18M ~Ft. Collins, CO –all 50

— 50 AirDisaster.com. Accident Database. Accident Synopsis 06301951.
— 50 Aviation Safety Network (ASN). Accident Description, United Flight 610, June 30, 1951
— 50 CAB. AIR. United Air Lines, Inc., – Fort Collins, Colorado, June 30, 1951.
— 50 Notable California Aviation Disasters. “The 1950s” Oct 23 2008 update.
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Narrative Information

AirDisaster.com: All 50 on-board United N37543 are killed – “The aircraft collided with Crystal Mountain after a navigational error by the flight crew in darkness.” (AirDisaster.com. Accident Database. Accident Synopsis 06301951.)

Aviation Safety Network: “United Flight 610 originated in San Francisco and was scheduled to Chicago, Illinois, with en route stops, among which were Oakland, Salt Lake City and Denver. The flight, which was carried out by DC-6 “Mainliner Overland Trail”, departed San Francisco on schedule at 19:15 and after stopping at Oakland proceeded to Salt Lake City, arriving there at 23:24. It departed Salt Lake City at 00:11, 26 minutes behind schedule due to the reloading of bulky cargo.

“The aircraft climbed to the cruising altitude of 15,000 feet. At 01:47, the flight reported having passed the Silver Crown fan marker (located 12 miles west of Cheyenne) and requested a lower altitude. ARTC [Air Route Traffic Control] cleared the flight down to 8500 feet. After crossing the Cheyenne range station at 15,000 feet the crew then executed a right turn to a heading of 210 degrees, descending to 8,500 feet. The correct heading for the airway to Denver however was 168 degrees.

“At 01:56 the flight reported reaching its assigned altitude. The DC-6 was now flying dangerously close to the mountainous terrain. At around 02:00 it struck the side of Crystal Mountain [Rocky Mountains]. After initial contact with the trees the aircraft continued to travel approximately sixty feet, at which point it struck the ground. From here it traveled in a straight line 225 feet, then bounced into the air again, and came to rest 465 feet farther on.

“One of the possibilities was that the captain made some wrong selections on the audio selector panel, silencing the Denver low frequency radio range signals and receiving the Denver Visual Audio Range (VAR). Such a mistake can easily be made because using the correct switches in a darkened cockpit is difficult and because both radio range signals are difficult to differentiate. Another possibility is that the ADF [Automatic Direction Finder] had been affected by the Fort Bridger radio range.”

“Follow-up / safety actions: The Denver low frequency and VAR signals were altered by the Civil Aeronautics Administration and United Air Lines adjusted the radio selector panels. United also implemented a programme emphasising route training and equipment qualifications.” (ASN, United Flight 610, June 30, 1951)

Civil Aeronautics Board Accident Investigation Report, 12-12-1951:
“The Accident

“United Air Lines Flight 610, a Douglas DC-6, N-37543, crashed 18 miles west-southwest of Fort Collins, Colorado, and 29 miles west of the centerline of Airway Amber 3, at approximately 0200, June 30, 1951. All of the occupants were killed and the aircraft was demolished.

“History Of The Flight
“Flight 610 of June 29, 1951, originated in San Francisco, California, and was scheduled to Chicago, Illinois, with en route stops, among which were Oakland, California, Salt Lake City, Utah, and Denver, Colorado. The crew consisted of Captain J R Appleby, First Officer H G Tower, Flight Engineer A T Petrovitch, and Stewardesses C J. Raymond and F. M. Smith. The flight departed San Francisco on schedule at 1915 and after stoping at Oakland proceeded to Salt Lake City, arriving there at 2324. It departed Salt Lake City at 0011, June 30, 1951, 26 minutes behind schedule due to the reloading of bulky cargo….There were five crew members, forth-four adult passengers and one infant on board….

“Investigation

“Investigation disclosed from the direction of the swath cut through the trees that the aircraft struck the side of Crystal Mountain while fling with its left wind low and on an approximate magnetic heading of 210 degrees. The altitude at the point of impact was found to be 8,540 feet MSL. After initial contact with the trees the aircraft continued to travel approximately sixty feet, at which point it struck the ground. From here it [end p.1.] traveled in a straight line 225 feet, then bounced into the air again, and came to rest 465 feet farther on. The aircraft was demolished, and aircraft parts and assemblies were strewn over a 1,400 foot area. Localized fires occurred after impact.

“An examination of the wreckage revealed that at the time of impact the landing gear and flaps were retracted. During this examination northing was found to indicate that there was any structural failure of the aircraft or its components prior to impact….

“The damaged engines and propellers were examined and these indicated that all four engines were developing considerable power when the impact occurred…. [p.2.]

“Probable Cause: The Board determines that the probable cause of this accident was that, after passing Cheyenne, the flight for reasons undetermined failed to follow the prescribed route to Denver and continued beyond the boundary of the airway on a course which resulted in the aircraft striking mountainous terrain.” (Civil Aeronautics Board File No: 1-0050, p. 5.)

Notable California Aviation Disasters:

Number 5 (tie) of California’s “10 Worst Crashes”
Date / Time: Friday, August 24, 1951 / 4:28 a.m.
Operator / Flight No.: United Air Lines / Flight 615
Location: Near Decoto (Union City), Calif.

“Details and Probable Cause: United Air Lines Flight 615 originated in Boston, Massachusetts, with stops in Hartford, Connecticut; Cleveland, Ohio; and Chicago, Illinois. From Chicago, the four-engine Douglas DC-6B airliner (N37550) continued west, bound for Oakland and San Francisco.

“Flying in patchy fog on the southeastern side of San Francisco Bay, the propeller-driven airliner had been cleared for an approach to Oakland Municipal Airport when it struck Tolman Peak, 14.8 miles southeast of the airport.

“The DC-6B impacted the hill at an elevation of about 983 feet at an estimated speed of 225 to 240 mph and cartwheeled into Dry Gulch Canyon, bursting into flames. All six crew members and 44 passengers, including two infants, died in the crash.

“An investigation of the accident found that neither of the DC-6B’s two low-frequency receivers had been tuned to the Oakland station, and the captain may have attempted to fly the plane by visual reference using the automatic direction finder (ADF). As a result, the airliner was flying well below the prescribed altitude for the area and was three miles off course.

“Fatalities: 50 — all 44 passengers and the crew of 6.” (Notable California Aviation Disasters. “The 1950s” Oct 23 2008 update.)

Sources

AirDisaster.com. Accident Database. Accident Synopsis 06301951. Accessed at: http://www.airdisaster.com/cgi-bin/view_details.cgi?date=06301951&reg=N37543&airline=United+Airlines

Aviation Safety Network, Flight Safety Foundation. Accident Description. United Airlines Flight 610 strikes Crystal Mountain 18M WSW of Fort Collins, CO, 6-30-1951 Accessed 6-24-2023 at: https://aviation-safety.net/database/record.php?id=19510630-0

Civil Aeronautics Board. Accident Investigation Report. United Air Lines, Inc., – Fort Collins, Colorado, June 30, 1951. Washington, DC: CAB, December 12, 1951, 10 pages. Accessed at: http://dotlibrary1.specialcollection.net/scripts/ws.dll?file&fn=8&name=*P%3A%5CDOT%5Cairplane%20accidents%5Cwebsearch%5C063051.pdf [Link inoperative on 6-24-2023 check.]
Accessed 6-24-2023 at: file:///C:/Users/Wayne/Downloads/dot_33418_DS1.pdf

Notable California Aviation Disasters. “The 1950s.” Oct 23 2008 update. Accessed at: http://www.jaydeebee1.com/crash50s.html